NEW YORK — In the days after a December blizzard paralyzed New York City, residents upset with the slow pace of the cleanup were further enraged by reports that the snow removal effort had been sabotaged on the night of the storm by disgruntled city sanitation workers.

But in a report released Friday, the city's anticorruption agency said that while its-five month probe of those allegations had uncovered some instances of wrongdoing – including a trip by one group of plow drivers to buy beer – it found no evidence that an organized work slowdown had taken place.

The city's Department of Investigation said it interviewed some 150 witnesses and reviewed 24 hours of video footage from surveillance cameras around the city, as well as GPS records and pictures and video submitted by residents, and found only a handful of instances where plows were either sitting still or traveling with their plows up for unexplained reasons.

The video appeared to show that the overwhelming bulk of the city's plowing fleet was in action, and that trucks seen sitting idle were actually stuck in the snow, the report said.

The report also raised questions about the credibility of the city council member who helped ignite a public furor over the rumored work stoppage.

After the Dec. 26 blizzard, City Councilman Dan Halloran gave an interview to the New York Post in which he claimed to have spoken with five city workers who confirmed there had been an organized work slowdown to protest budget cuts.

Halloran subsequently told The Associated Press he had been visited by three sanitation workers who complained that supervisors upset about a round of pending demotions had told them to go easy on the night of the storm and "basically been giving them a green light not to do their job."

Halloran, a tea party Republican from Queens, said he also spoke with two Department of Transportation supervisors who claimed they had been instructed to sit idle for hours, rather than get to work plowing streets.

In its report, however, the Department of Investigation said that when it interviewed the two transportation supervisors, they strongly disputed Halloran's account. Both said they had no knowledge of any work slowdown and were caught off-guard when Halloran unexpectedly grilled them about it during a casual lunch meeting.

"Supervisor 2 said that the meeting was very uncomfortable and he felt like Mr. Halloran was `annoyed' that they did not have any information that would confirm a slowdown. He said the encounter was brief, several minutes," the report said.

The supervisors also told investigators they were shocked when news articles began appearing in which Halloran described them as whistleblowers.

"Supervisors 1 and 2 also said they were upset because Mr. Halloran's statements made it seem as though they were part of a group of five City employees who provided Mr. Halloran with concrete information to corroborate a slowdown when, in fact, they asserted that is not what they said," the report said. Both men denied making any statements about being held back on purpose during the storm.

Halloran has declined to reveal the names of the three other city workers with whom he allegedly spoke. Initially, he claimed he was doing so to protect their privacy. The DOI report said Halloran later told investigators he only knew the workers' first names and was having difficulty contacting them. Finally, he said publicly that since he was a lawyer, and the men had come to him for advice, legal ethics barred him from revealing who they were.

Asked for comment, Halloran issued a statement through his spokesman that didn't address whether he had mischaracterized his conversations with the workers.

"Disturbing questions remain about why plows went down streets with their blades up or sat unmoving for hours as the snow fell," it said. "My constituents expect me to shed a light on problems and come up with solutions, and I am going to do that, even when it makes the powers that be uncomfortable."

Harry Nespoli, president of the Teamster's local that represents sanitation workers, said he thought the Department of Investigation report vindicated the plow drivers.

"But all it does is make me more angry," he said, adding that hard-working Sanitation Department employees had to endure insults in the street because of the episode. "I think Mr. Halloran should turn around and address the sanitation workers in this city. I just don't think (what he did) was right."

The report did provide some criticism of the way New York City officials handled the storm. An unusual number of plows became stuck in the snow at some point, and the report questioned whether too many drivers were instructed to sit with their vehicles for many hours until help arrived, rather than being put to work in some other fashion. The probe also found that 44 percent of the snow chains deployed on plows broke during the cleanup.

Investigators also recovered surveillance video, first identified by the New York Post, showing one sanitation crew buying beer at a convenience store in Brooklyn while they were still in uniform and on the job.

Disciplinary actions have begun against those workers, city officials said.